Public and private communication networks use switching systems, sometimes referred to as central office and private branch exchange switching systems, for interconnecting calling parties with called parties. Typically, a calling party is connected to a switching system which responds to dialing instructions generated by the calling party by selectively interconnecting the calling party with called parties identified by the dialing instructions.
Switching systems interconnected by communication networks serve customers wherein each customer has calling parties that are connected via lines and trunks served by the switching system and over other trunks of the switching systems through the communication network and other switching systems with lines of called parties. Oftentimes, customers desire that various calling parties be given access to various switching system facilities assigned the customer that may be denied access thereto by other calling parties. For example, a customer may desire that only selected calling parties be given access to switching system trunk groups connected with a private communication network or facilities of the customer which other calling parties are to be denied access.
A customer desiring to restrict access to the customer assigned facilities contacts the local telephone company and requests that access of various customer assigned facilities be limited to selected parties. The local telephone company installs hardware and software changes in the switching system to control the switching system to deny access of ones of the customer lines to the customer assigned facilities. A problem arises in this arrangement in that customer telephone lines, not the calling parties, are denied access to the restricted facilities. Any calling party may access the restricted facilities, whether permitted or not, by simply locating and using a customer line or trunk that has been given access. Another problem arises in that the customer must contact the local telephone company to change or install the denial access changes in the switching system.